Process of storing and handling acetylene solutions



United States Patent PROCESS OF STORING AND HANDLING I ACETYLENESOLUTIONS Karl Winnacker, Konigstein, and Arthur Wolfram, Frankfurt,Germany, amignors to Knapsack-Griesheim Alttlengesellschaft, Knapsack,near Koln, Germany, a company of Germany No Drawing. ApplicationNovember 29, 1955 Serial No. 549,855

Claims priority, application Germany February 14, 1951 7 Claims. (Cl.252-4) This application is a continuation-in-part application of ourapplication Ser. No. 271,076, now abandoned, which describes the storageor transportation of liquid acetylene which is dissolved at atemperature below -80 C. in at least one solvent for acetylene, forexample acetaldehyde. The solvent being present in an amount of at leastabout 22 percent calculated upon the weight of the acetylene.

The present invention relates to the safe handling, storing ortransporting of liquid acetylene and comprises storing and handlingacetylene at temperatures below about -80 C. and dissolved in at leastone solvent for acetylene with the solvent being present in an amount ofat least about 22 percent calculated upon the weight of the acetylenesolution. The solutions of acetylene in mixtures of solvents are new.They are likewise an object of the present invention.

We have found that acetylene can safely be handled, stored andtransported in the liquid state in the form of solutions which areobtained by introducing gaseous acetylene at a temperature below about-80 C. into a solvent mixture capable of readily dissolving theacetylene and consisting of acetaldehyde and methyl isobutyl ketoneand/or methyl ethyl ketone and additionally of acetone.

Since acetylene, and particularly liquid or solid acetylene, belongs tothe class of violently explosive compounds, it cannot be stored as otherhydrocarbons under pressure in steel bottles unless these steel bottlescontain a filling material and the acetylene is compressed into asolvent such as acetone. Such acetylene, designated as dissolvedacetylene gas, possesses the disadvantage that only a relatively smallquantity may be stored in a bottle and that a large and expensive stockof bottles must therefore be maintained. Considerable expense occursthrough frequent and requiredrepairs to the steel bottles and thevalves. Many attempts have already been made to convert the acetyleneinto the solid form and to store it is that form, but this has beenimpossible in practice in view of the explosive property of the product.According to another suggestion, the liquid acetylene should be storedin a fully enclosed pressure reservoir cooled by means of solid carbondioxide and acetone. This process is not satisfactory for industrialpurposes because it is too dangerous.

The solvent mixtures used according to the present invention are liquidat temperatures between about --80 C. and about -1'15 C. The componentsof said mixtures have a boiling point above 0 C.

If the process of this invention shall be economical, the amount of thesolvent used must be as small as possible. Hence, it is necessary toemploy temperatures as low as possible. It is generally satisfactorythat about two and a half to three and a half times the quantity byweight of acetylene be present with respect to the weight of the solventor solvents, i.e. the solvent or solvents must be present at least in aquantity of about 22 percent, calculated upon the weight of theacetylene solution.

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Preferably the solvent represents about 25-50% by weight of theacetylene solution and the optimum amount of solvent is about 25-33%.The acetylene is preferably present in an amount of at least about 50%and preferably about 67 to especially 70% or more. However, it has beenfound that acetylene crystals may separate from very cold solutionswhereby the danger of explosion is highly increased.

According to the present invention, it is now possible to transport orto store large quantities of acetylene for a prolonged time, since asolution of acetylene cooled to about -1l0 C. can be stored far longerin the liquid state than a solution of a higher temperature. If themelting point is, for example, at l40 C., the temperature of theacetylene solution may rise for 60 degrees centigrate, but theexplosion-proof character of the solution is still maintained. Foreconomical reasons, however, extremely low temperatures will be appliedfor the preparation of the cooled solutions only exceptionally since,when solvents are used which at about 1l5 C. are just still liquid, thesolutions have a sufiiciently large capacity to maintain a temperaturebelow C., which temperature is necessary for storing or transporting.Also, the costs increase as the temperature of the solvent is loweredwhen preparing the acetylene solution. The dissolved liquid acetylenecooled e.g. to temperatures of about l15 C. can be transported or storedfor many days in a well insulated vessel without undergoing a loss ofacetylene and solvent worth mentioning. This amounts to a considerablesaving in comparison with the hitherto known processes. The transport ofthe dissolved acetylene is thus made bearable from an economical pointof view, and this the more so, since simple, well insulated reservoirshaving relatively thin walls may be used. Neither during the manufactureof the dissolved liquid acetylene is an application of pressurenecessary, nor is a pressure produced in an amount worth mentioningduring the storing at a temperature of about -80 C. or below. If it isintended to store the dissolved, liquid acetylene for a prolongedperiod, it is recommended to apply a refrigeration by means of acorresponding cooling agent. If vessels having thick walls are applied,it is, of course, also possible to dissolve the acetylene withapplication of pressure. The application of pressure is, however, notnecessary. It is also possible to maintain the solutions of liquidacetylene even under reduced pressure, but above the boiling point ofacetylene. However, this procedure is not very economical.

If the solvent boils at a sulficiently high temperature, for instance at0 C., it is also possible, when the gaseous acetylene is eventuallyused, to obtain a gas, substantially free from solvent. The solutionsaccording to this invention consist of acetylene and at least 22 percent(calculated on the weight of the solution) of a solvent mixture,comprising at least 70 percent and at most 99.5 percent of acetaldehyde.

The mixtures of solvents used according to the present invention containat least about 70 percent and at most 99.5 percent of acetaldehyde. Theremaining parts consist of methyl ethyl ketone and/0r methyl isobutylketone in an amount of about 0.5 to about 25 percent and of acetone inan amount of about 0.1 to about 15 percent, the percentage data beingcalculated on the total amount of the solvent mixture in which theacetylene will be dissolved.

It is to be understood that where solvent mixtures are described inwhich the total amount of the upper limits of all percentage figures oithe solventsother than acetaldchyde is higher than 30"percent, the totalamount of these components in the solvent mixture shall be not higherthan 30 percent.

Preferably, mixtures are used of about 70 to about 98.9 percent ofacetaldehyde, of about 1 to about 22 percent of methyl ethyl ketoneand/or methyl isobutyl ketone and of about 0.1 to about 15 percent ofacetone. Furthermore, it has been found suitable to use mixtures ofsolvents which contain at least about 70 and at most about 99.3 percentof acetaldehyde, between about 0.1 to about 15 percent of acetone,between about 0.5 to about 20 percent of methyl ethyl ketone and betweenabout 0.1 and about 8 percent of methyl isobutyl ketone. Other mixturesof solvents which can be used are those which contain between about 70and about 99 percent of acetaldehyde, between about 0.4 and about 8percent of acetone, between about 0.5 and 20 percent of methyl ethylketone and between about 0.1 to about 8 percent of methyl isobutylkctone; the total amount of methyl isobutyl ketone being never higherthan about 25 percent.

Especially suitable are solvent mixtures which contain between about 70and about 90 percent of acetaldehyde" and in which the total amount ofthe other components is between about 10 and about 30 percent, everycomponent itself being added in an amount within the limits given above.

The mixtures of this invention are capable of readily dissolving theacetylene and are still liquid at temperatures between about 115 C. to--80 C. They yield solutions of acetylene which are still liquid at verylow temperatures and in many cases at far lower temperatures than thosedescribed in the parent application.

It is desirable to keep as low as possible the temperature at which asolidification of the acetylene dissolved in the solvent or in themixtures of solvents occurs, since the solidified solution or a solutioncontaining acetylene crystals can no longer be handled with completesafety. Already with some solvents, for instance, acetaldehyde, it ispossible to obtain solutions which solidity only-at a temperatureconsiderably below --80 C. With the mixtures of solvents as described inthe present 'applb cation, the solidification point is, in general,pressed down to a lower degree. The quantitative proportion of thevarious solvents in these mixtures may vary within the wide limitsmentioned above. It is particularly suitable to use the variousconstitutents in such quantities that eutectic mixtures are formed.

The quantitative proportions in which the solvents or the mixtures ofsolvents on the one hand and the acetylene on the other hand shall beused may likewise vary to a large extent. The quantity of the solvent orof the mixtures of solvents may be superior to that of the acetylene.

Since the acetylene from the solution may be used directly for fillingbottles of dissolved acetylene gas, it is advisable, during themanufacture of the acetylene solution, to use a well purified acetylene,in order to avoid a purification at a later date. If, the stepsdescribed herein are strictly observed, the solutions of liquidacetylene will not detonate with the detonators usually applied inexplosive tests.

With the mixtures of acetylene and solvents described in Examples l-14hereafter, detonation tests were made. Furthermore, the said mixtureswere subjected to tests which consisted in severely heating the solutioncontained in a nearly sealed metal tube. The metal tube of a length ofabout 40 centimeters and containing 1 liter of the solution, was heatedin a slightly inclined position with 6 strong Teclu burners. Theacetylene with the solvent was permitted to escape through an apertureof a diameter of 1.5 millimeters at one extremity of the tube and burntofi merely with a strong flame, whereas meta-dinitrobenzene detonatedwhen tested in the same manner. It must be emphasized thatmeta-dinitrobenzene is not regarded as an explosive for purposes oftransport.

The industrial progress attained by the process of the present inventionis thus proved.

The following examples serve to illustrate flie'invention,

4 but they are not intended to limit tberetqtheparts being by weight:

Example I grams of the mixgrams of percent turn of dlssol'vsd my weight.s n 64 (hi1: without acetylene lound melting p i t. C.

(2) 10.0 percent methyl ethyl ketoue+6.0 percent acetoilet-81.0 percentacetatdehyde (3) 10.0 percent methyl ethyl ketonu+3.0 percentacetone+8L0 percent ucetaldebyde (4) 20.0 percent methyl ethylimmune-1.0 percent acet.0ue+79.9 percent acuteldehyde (5) 20.0 percentmethyl ethyl ketouo-I-7.0 percent ace tone +73;0 percent acetatdehydc(0% 2.0 percent methyl isoutyl kctoie-l-ton percent; ao3tone+83.0percent neataliehyde (7) 14.0 percent methyl lso butyl ketonet-iupercent acetune+82.0 perceutaceb alzleh d y 15:2 (8) 20.0 percent-10; methyl isobutyl ketone+L0 percent acetone-H911 percent acetaldeiyde(9) 2.0 percent methyl ethyl kotone +1.0 percent methyl isobutylketone+l3.0 percent acetone+84.0 percent acetaldehyde (in) 12.0 percentmethyl ethyl ketone+2.5 percent methyl lsobutyl ketone +2.5 percentscratched-83.0 percent acetaldehyde V (11) 20.0 percent methyl .eths lketone+0.5 percent methyl lsobutyl ketone +0.5-perouut acetone-Maoporeenbacetaldehyde (13012.0 percent methyl ethyl ketone+20 percentmethyl tsooutyl ketone +3.0 percent costumes-83.0

ercen't acetaldehyde (I ).15.0 percent methyl ethyl ketonc+L5 percentmethyl lsobutyl ketone +45 percent acet0ne+79.0 percent acct-aldehyde a(14) 19.0 percent methyl ethyl ketoue+0.5 percent methyl lsobutyl ketone+6.5 percent acetone-+740 percent acetaldehyde 15.8 3&1 0 -l05 We claim:

1. The process of storing and handling acetylene solutions with a highconcentration or at'le'ast 50% anemone at low temperature atsubstantially normal pressure for prolonged periods of time withoutdanger of explosion which comprises dissolving, storing and handlingacetylene at temperatures below about C. in a mixture of solvents foracetylene, which consists or about 70 to about 99.4 percent assessmentas, aboutQS to abo'ut 2.5 percent of a ltctone selected from the" groupconsisting of methyl ethyl ketone and methyl isobutyl ketone andmixtures thereof and of about 0.1 to about IS percent of acetone, saidmixture of solvents'being presem'in an amuunt'of'between about 22 and 50percent calculated on the weight of the acetylene solution, and thesolution being maintained above the solidification point.

2. The process of storing and handling acetylene solutions with a highconcentration of at least 50% acetylene lat low temperature atsubstantially normal pressure for prolonged periods of time withoutdanger of explosion which comprises dissolving, storing and handlingacetylene at temperatures below about 80 C. and under substantiallyatmospheric pressure in a mixture of solvents for acetylene, whichconsists of about 70 to about 99.4 percent of acetaldehyde, about 0.5 toabout 25 percent of a ketone selected from the group consisting ofmethyl ethyl ketone and methyl isobutyl ketone and mixtures thereof andof about 0.1 to about 15 percent of acetone, said mixture of solventsbeing present in an amount of between about 22 and 50 percent,calculated on the weight of the acetylene solution, and the solutionbeing maintained above the solidification point.

3. The process of storing and handling acetylene solutions with a highconcentration of at least 50% acetylene at low temperature atsubstantially normal pressure for prolonged periods of time withoutdanger of explosion which comprises dissolving, storing and handlingacetylene at temperatures below about 80 C. in a mixture of solvents foracetylene, which consists of about 70 to about 99.3 percent ofacetaldehyde, about 0.1 to about 15 percent of acetone, about 0.5 toabout 20 percent of methyl ethyl ketone and of about 0.1 to about 8percent of methyl isobutyl ketone, the total amount of methyl ethylketone and methyl isobutyl ketone being not higher than about 25percent, said mixture of solvents being present in an amount of at leastabout 22 percent and at most about 50 percent, calculated on the weightof the acetylene solution, and the solution being maintained above thesolidification point.

4. The process of storing and handling acetylene solutions with a highconcentration of at least 50% acetylene at low temperature atsubstantially normal pressure for prolonged periods of time withoutdanger of explosion which comprises dissolving, storing and handlingacetylene at temperatures below about 80 C. in a mixture of solvents foracetylene, which consists of about 70 to about 99.0 percent ofacetaldehyde, about 0.4 to about 8 percent of acetone, about 0.5 toabout 20 percent of methyl ethyl ketone and about 0.1 to about 8 percentof methyl isobutyl ketone, the total amount of methyl ethyl ketone andmethyl isobutyl ketone being not higher than about 25 percent, saidmixture of solvents being present in an amount of at least about 22percent and at most about 50 percent, calculated on the weight of theacetylene solution, and the solution being maintained above thesolidification point.

5. The process of storing and handling acetylene solutions with a highconcentration of at least 50% acetylene at low temperature atsubstantially normal pres sure for prolonged periods of time withoutdanger of explosion which comprises dissolving, storing and handlingacetylene at temperatures below about 80 C. in a mixture of solvents foracetylene, which consists of about to about 90 percent of acetaldehydebetween about 0.1 and about 15 percent of acetone and between about 0.5and about 25 percent of a compound selected from the group consisting ofmethyl ethyl ketone and methyl isobutyl ketone and mixtures thereof, thetotal amount of acetone, methyl ethyl ketone, and methyl isobutyl ketonebeing between about 10 and about 30 percent, said mixture of solventsbeing present in an amount of at least about 22 percent and at mostabout 50 percent calculated on the weight of the acetylene solution, andthe solution being maintained above the solidification point.

6 The process of storing and handling acetylene solutions with a highconcentration of at least 50% acetylene at low temperature atsubstantially normal pressure for prolonged periods of time withoutdanger of explosion which comprises dissolving, storing and handlingacetylene at temperatures below about C. in a mixture of solvents foracetylene, which consists of about 70 to about 99.4 percent ofacetaldehyde, about 0.5 to about 25 percent of a ketone selected fromthe group consisting of methyl ethyl ketone and methyl isobutyl ketoneand mixtures thereof and of about 0.1 to about 15 percent of acetone,said mixture of solvents being present in an amount of between about 25and 50 percent calculated on the weight of the acetylene solution, andthe solution being maintained above the solidification point.

7. The process of storing and handling acetylene solutions with a highconcentration of at least 50% acetylene at low temperature atsubstantially normal pressure for prolonged periods of time withoutdanger of explosion which comprises dissolving, storing and handlingacetylene at temperatures below about 80 C. and under substantiallyatmospheric pressure in a mixture of solvents for acetylene, whichconsists of about 70 to about 99.4 percent of acetaldehyde, about 0.5 toabout 25 percent of a ketone selected from the group consisting ofmethyl ethyl ketone and methyl isobutyl ketone and mixtures thereof andof about 0.1 to about 15 percent of acetone, said mixture of solventsbeing present in an amount of between about 25 and 50 percent,calculated on the weight of the acetylene solution, and the solutionbeing maintained above the solidification point.

References Cited in the file of this patent UNITED STATES PATENTS UNITEDSTATES PATENT OFFICE CERTIFICATE OF CORRECTION Patent No 2 ,925 384February 16 1960 Karl Winnacker et al.

It is hereby certified that error appears in the-printed specificationof the above numbered patent requiring correction and that the saidLetters Patent should read as corrected below.

Column 4 in the table column 1 thereof line 3 of Example (4), for "79.9"read 79.0

Signed and sealed this 30th day of August 1960.

( SEAL) Attest:

ERNEST W. SWIDER ROBERT C. WATSON Attesting Oflicer Commissioner ofPatents

1. THE PROCESS OF STORING AND HANDLING ACETYLENE SOLUTIONS WITH A HIGHCONCENTRATION OF AT LEAST 50% ACETYLENE AT LOW TEMPERATURE ATSUBSTANTIALLY NORMAL PRESSURE FOR PROLONGED PERIODS OF TIME WITHOUTDANGER OF EXPLOSION WHICH COMPRISES DISSOLVING STORING AND HANDLINGACETYLENE AT TEMPERATURES BELOW ABOUT -80*C. IN A MIXTURE OF SOLVENTSFOR ACETYLENE, WHICH CONSISTS OF ABOUT 70 TO ABOUT 99.4 PERCENT OFACETALDEHYDE, ABOUT 0.5 TO ABOUT 25 PERCENT OF A KETONE SELECTED FROMTHE GROUP CONSISTING OF METHYL ETHYL KETONE AND METHYL ISOBUTYL KETONEAND MIXTURES THEREOF AND OF ABOUT 0.1 TO ABOUT 15 PERCENT OF ACETONE,SAID MIXTURE OF SOLVENTS BEING PRESENT IN AN AMOUNT OF BETWEEN ABOUT 22AND 50 PERCENT CALCULATED ON THE WEIGHT OF THE ACETYLENE SOLUTION, ANDTHE SOLUTION BEING MAINTAINED ABOVE THE SOLIDIFICATION POINT.